/Engine/Plugins/Experimental/SlateScreenReader/Source/SlateScreenReader/Public/SlateScreenReaderEngineSubsystem.h
Returns true if the passed in screen reader user Id is already registered. Else false is returned.
[UFUNCTION](Programming/UnrealArchitecture/Reference/Functions)(BlueprintCallable, Category="SlateScreenReader") bool IsUserRegistered ( UPARAM(DisplayName="Screen Reader User Id") int32 InUserId ) const